Latch



pr 1952 N. A. WELCH 2,5%,647

LATCH F'led Nov: l2, 1948 2 SHEETS--SHEET l m ATTORNEYS April l, l952 N. A. WELCH 2,591,647

LATCH Filed Nov. 12, 1948 FIG. 5.

2 SHEETS--SHEET 2 INVENTOR /V/cHo/.As A. iMac/1 ATTORNEYS Patented Apr. l, 1952 LATCH Nicholas A. Welch, West Hartford, Conn., assignor to The American Hardware Corporation, New Britain, Conn., a corporation of Connecticut Application November 12, 1948, Serial No. 59,461

2 Claims.

My invention relates to a latch mechanism, and in particular to a unitary structure which may be inserted into and mounted upon an edge of a door and which may cooperate with actuating elements of a lock mechanism.

It is an object of the invention to provide an improved device of the character indicated.

It is another object to provide a door-latch construction with improved means to resist picking of the latch.

It is a more specic object to provide an improved auxiliary latch mechanism.

It is a general object to meet the above objects with a relatively simple construction that may be inexpensively fabricated.

Other objects and various further features of the invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunctionwith the accompanying drawings. In said drawings, which show, for illustrative purposes only, a preferred form of the invention: Y

Fig. l is a longitudinal sectional view through the case of a latch structure incorporating features of the invention;

Fig. 2 is another longitudinal sectional view of the latch of Fig. 1, but taken substantially in the plane 2-2 of Fig. l;

Fig. 3 is a sectional View taken in the plane 3 3 of Fig. 1;

Fig. 4 is a view in perspective of the latch mechanism of Fig. 1, with the case removed in order more clearly to show the working parts;

Fig. 5 is a longitudinal sectional View through the case of a modified latch structure incorpo- :rating features of the invention;

Fig. 6. is a view in perspective of the latch mechanism of Fig. 5, with the casing removed, as in Fig. 4; and

Fig. '7 is a sectional view taken in the plane '1 -'I of Fig. 5.

Briey stated, mv invention contemplates an improved safety or anti-picking latch construction wherein a main latch bolt and Ian auxiliary latch bolt cooperate to dog the mechanism against picking when the door is shut. The main bolt and the auxiliary bolt may be longitudinally slidable relatively to each other, and the retracting means for the main bolt may include a lostmotion connection. Interfering means may be included to interfere with retracting displacement of the main bolt when in a first position, and not to interfere with such displacement when in a second position. Resilient means may normally urge both bolts outwardly and also normally urge the interfering means into said first position. Cam means may cooperate in a rst manner between the interfering means and the retractor for the main bolt, to move the interfering means away from said first position and towards said second position upon a r actoractuated withdrawal of the main bolt. e cam means may also cooperate in a second manner between the interfering means and the auxiliary bolt to move the interfering means away from said first position for an outward displacement of said auxiliary bolt.

Before describing preferred forms of my invention in detail, it may be Well to outline their mode of operation for several possible conditions.

To begin with, let it be assumed that the door is open and that both the main bolt and the auxiliary bolt are in their normally outwardly displaced positions. With both bolts thus outwardly displaced, the cam means may be holding the interfering means out of position to interfere with retraction of either of the bolts. The door may, therefore, be closed and when either or both of the bolts hit th'e strike plate, they may ride upon the strike plate and may thus be inwardly displaced. When fully closed, the strike plate may hold back the auxiliary bolt in its retracted position and, at the same time. allow the main bolt to assume its outward or locking position, that is, its position extending through the strike plate. As the main bolt thus moves from its retracted toits extended position, the cam means may be ineffective to keep the interfering means in its second position, and the interfering means will therefore be moved or allowed to move into the first or interfering position, that is. into the position which will prevent subsequent retraction of the main bolt merely upon inwardly displacing the main bolt. When the .door is closed, therefore, it will be impossible to pick the lock by attempting to push in the main bolt.

In manually opening the door, the lock mechanism (not shown or described herein) for the door will be suitably actuated so as to move the retractor means of the latch mechanism. This retractor means may cammingly cooperate with the interfering means to displace the interfering means away from said rst position upon retractor actuation; thus, the retractor may be effective to withdraw the latch bolt, while pushing the latch bolt may be ineffective to Withdraw the latch bolt. s

Referring to the drawings, my invention is shown in application to a unitary latch structure to be sunk into and mounted ush with the front edge I of a door, and the latch may be arranged to cooperate with a strike plate 9 in a door frame. 'I'he latch housing may comprise a front plate I'I which may be secured to the door, and a case I2 which may be crimped, Welded, or otherwise secured to the front plate I I and which may contain the entire latch mechanism. A main bolt I3 may be sldably guided within the latch case, and an auxiliary bolt I may be guided in a groove I5 in the main bolt I3. Both bolts It-Ili may be normally resiliently urged into an outward position; for this purpose, a compression spring I6 may be located by a stud II on the Imain bolt I3 to urge the main bolt I3 outwardly, and a second coil spring I8 may engage the back end of the auxiliary bolt I4 similarly to urge the auxiliary bolt. The main bolt may carry or be formed with a tail 2i] extending longitudinally of the bolt I3 and, if desired, out the back end of the latch case i2. For actuating purposes, the bolt tail may be formed with outwardly extending ears or projections 2i, which in the form shown are designed to engage plates 22 of the retractor carriage of a lock mechanism (not shown). A suitable lock lmechanism for actuating the present latch i Y hown and described in complete detail in my co-pending patent application, Serial No. 74,963, led February 7, 1949.

For a purpose which will later be clear, the

retractor means for the main bolt may include a further member having a lost-motion connection to the main bolt or to a part movable with the main bolt. Such auxiliary retractor means may be in the form of a tail piece 23 having ears 24 like the ears 2l of the main bolt tail 2t, so as also to engage the retractor plates 22 of the lock mechanism. In order to provide the desired lostmotion connection I have shown mutually abutting means 25-26 on the auxiliary tail 2E and on the main-bolt tail 2t, respectively. Both tail pieces 29--23 may be formed with extended necks to pass through a guiding aperture 2 at the bottom or rear end of the latch case and, although I prefer that there shall be no binding between the main-bolt tail 2i] and the latch case and between the auxiliary bolt tail 23 and the latch case, I further prefer that this reduced or neck portion for the main-bolt tail 2E shall be narrower than the corresponding dimension of the auxiliary tail 23. This fact is illustrated in Fig. 2 by the dotted lines 28, and it will be appreciated that as long as the neck of the auxiliary bolt tail is wider than the neck of the main-bolt tail, the auxiliary-bolt tail will serve to prevent any possible binding between the latch case and the main-bolt tail 26 and between the retractor plates 22 and the main-bolt tail 2U, thus absolutely assuring the freest possible sliding displacement of the main bolt.

In order positively to locate the auxiliary-bolt tail, it may be formed, at one end, with a sleevelike portion loosely wrapped around and embracing part of the main-bolt tail 2a. This sleeve portion may provide the abutment 25 on the auxiliary-bolt tail 23, as will be clear. The abutment 2 on the main-bolt tail 2G may be a separate piece passing through or otherwise extending transversely of the main-bolt tail, but in the form shown the abutments 223 are merely integral lugs on the main-bolt tail 20.

In order to provide a means for clogging or for obstructing an inward displacement of the main bolt I3, I may employ interfering means in the form of a bracket 30. The bracket Sii may comprise a single piece bent to form substantially ra 4 right angle, with legs 3| movable into and out of possible interfering relation with the main bolt I3. In Fig. l, the solid outlines for the interfering bracket 39 represent a rst position thereof, with the arm 3i' poised to intercept the bolt I3 the dot-dashed outline 3l represents another position of the bracket 3), with the arm SI out of interfering relation with the main bolt I3. For the form shown, I prefer normally to urge the bracket into or toward the first or interfering position, and for this purpose I may utilize .the spring I6, which, it Will be recalled, serves also to urge the main bolt I3 outwardly. The spring I6 may thus abut the other arm 32 of the bracket 33 and may be suitably located upon a dimple 33 on said arm 32. It will be appreciated that the spring I6 may normally urge the bracket 30 to rotate clockwise (in the sense of Fig. 1) about the fulcrum line determined by abutment of the bend of bracket 30 with the bottom of latch case I2, as at 34. By forming the arm or base 32 of bracket 30 with a contour more or less conforming with that of the interior of the latch case, the bracket 3S may be self-locating, and no special pivot means need be provided for bracket 3o, as will be clear.

In accordance with a feature of the invention, I provide cam means to cooperate between the interfering means 3B and the retractor tail 23 in order to move the interfering means 3i] away from the interfering position and towards a noninterfering position upon a retracting displacement of the retractor tail 23, as when the lock mechanism (not shown) is actuated. The cam means may further cooperate between the interfering means 30 and the auxiliary bolt I4 to allow the interfering arm 3l4 to move toward the interfering position upon a retracting displacement of the auxiliary bolt I4.

In order to effect this desired camming relationship, I show a rst cam means co-acting between the interfering bracket 30 and the retractor tail 23. A cam surface in the form of a flat slope 35 may thus be formed on one or both sides of the interfering bracket, and this surface may be poised to engage a lug or outward projection 31 formed with the sleeve portion 25 of the retractor tail 23. It will be appreciated that, as the retractor tail 23 is retracted (as by actuation of the lock mechanism), the lug 31 may substantially immediately engage the cam surface 35 and that by providing sufficient longitudinal clearance (designated generally by A in Fig. 1) between the end of the interfering arm SI and a part of the bolt I 3, the interfering arm 3i may be forced out of possible engagement with the bolt I3 upon such lock-actuated retraction.

As indicated, cam means may cooperate further between the interfering bracket 30 and the main bolt I4. Such cam means may comprise a wedge 38 with a straight sloping surface to be carried with the auxiliary bolt I4 and positioned for camming engagement with a transverse projection 39 on each arm 3l of the interfering bracket 30. The cam surface 38 may serve to move the interfering arms SI away from interfering position upon an outward displacement of ,the auxiliary bolt III; conversely, when the auxiliary bolt is being retracted, as by engagement with the strike plate 9, the cam surface 33 may allow the interfering arms 3l to return to the interfering position or at least to seek to return to the interfering position. It will be appreciated that if the door isv open both bolts will be extended, and the arms 3i will be held out of interfering position, with the lugs 39 thereof riding upon a longitudinally extensive surface 40 adjacent to the cam surface 38 on the auxiliary bolt I4. As the door is being closed, the main bolt I3 will ride up the strike plate 9, and the interfering arms 3l will begin to ride off the ledge 48 and onto the cam .surface 38. With proper design, the cam surface 38 may not allow the interfering arms 3l to reach an interfering position under these circumstances, and the cam surface 38 may therefore only allow the interferng arms 3| to ride freely along the extensive flat surface 4i of the main bolt. When the door reaches its closed position and the main bolt springs outwardly to secure the door, the auxiliary latch I4 may be held up by the strike plate 9; and, as soon as the outer tips of the interfering arms 3l ride oif the back end of the main bolt I3, the force of spring I6 may assure the interfering arms 3l freedom to seek the interfering position shown in Fig. 1, thus rendering the latch pickresistant.

In Figs. 5, 6, and 7 I show a modified latch construction which may generally resemble the latch of the preceding figures. The structure of Fig. 5 may thus include a main bolt 50 resiliently outwardly urged by a spring 5| and housed within a case 52. The main bolt 50 may be retracted by a main-bolt tail 53. An auxiliary bolt 54 may also be slidable within the case 52, and in the drawings the auxiliary bolt 54 is shown in its retracted position, as held by a strike plate 55 (when the door is closed). A spring 56 may normally urge the auxiliary bolt 54 outwardly. As in the case of the previously described arrangement, the latch assembly of Fig. 5 may include interfering means in the form of a bracket or member 57 resiliently held by the spring 5I so that its interfering arms 58 are in position to interfere with retraction of the main bolt 50 whenever the auxiliary bolt 54 is held retracted, as in Figs. 5 and 6.

In accordance with a feature of the invention, the arrangement of Figs. 5, 6, and 7 may utilize a single cam means to produce, on the one hand, a shifting of the interfering arms 58 out of interfering position whenever the auxiliary latch bolt 54 is released to assume its outer position and, on 'the other hand, to shift the interfering arms 58 again out of interfering position upon a manual retraction of the main bolt, as by retractor means (not shown) cooperating with a tail piece 59 on an auxiliary retractor member 60. The retractor member 60 may include at its forward end a sleeve-like portion 6l with projections or ears 62 bent around the main-bolt tail piece 53 and facing each other (see Fig. 7).

The single cam means which characterizes the arrangements of Figs. 5, 6, and 7 may be carried by or formed integrally with the interfering bracket 51. As shown, this single cam means comprises a sloping surface on a lug or shelf 63 bent from the outer sides of the interfering arms 58. To cooperate with this surface 63 a suitable ledge 64 may be formed with or carried by the rear end of the auxiliary bolt 54. It will be seen that, if the auxiliary bolt 54 is allowed to displace outwardly from the positions shown in Figs. 5 and 6, the ledge 64 may substantially immediately intercept the cam means 63 so as to compel displacement of the interfering arms 58 away from possible interfering relation with the main bolt 58. In the forms shown, the ledge 64 is sufciently extensive to provide a means for keeping the interfering arms in their downwardly displaced position, even when the auxiliary bolt 54 is in its fully extended position, as when the door is open and the latch is not actuated.

In addition to the above-described cooperation with the ledge 64 of the auxiliary bolt 54, the cam means 63 max7 also cooperate with a part of the auxiliary retractor 60. In the form shown, such part is formed as an upwardly sloping projection 66 on an outwardly bent lug or ear 61 at the forward end of the sleeve portion 6|. It will be seen that, upon retraction of the auxiliary retractor 60, the underside of the projection 66 may intercept the forward edge of the cam means 63 and that, upon continued retraction of the auxiliary retractor 60, the interfering bracket 51 will be displaced downwardly, that is, rocked from the position shown and into a position in which the interfering arms 58 will no longer Iblock retraction of the main bolt 50. As in the case of the previously described'arrangement, the mainbolt tail 53 may include an integral abutment 68 to be engaged by the sleeve 6i as the auxiliary retractor is retracted; and, of course, the relation between projection 66 of the cam means 63 is preferably such that the interfering arms 58 will be cammed out of interfering relation with the bolt 5i) before the bolt 50 has been retracted as far as the outer or forward limit of interfering arms 58.

It will be appreciated that I have described ingenious unitary latch constructions utilizing parts that may be inexpensively fabricated. The mechanisms incorporate improved means to resist the picking of a door latch, and the construction of the various cam surfaces will be appreciated as contributing to prolonged trouble-free service.

While I have described my invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as dened in the claims which follow.

I claim:

1. In a latch device of the character indicated, a latch case, a main bolt longitudinally slidably guided in said case, a longitudinally extending tail for said bolt and including lug means projecting through an end of said case for retracting actuation by a retractor carriage, an auxiliary bolt longitudinally slidably guided in said case, a sleeve longitudinally slidably guided on said bolt tail and including lug means projecting through said end of said case for retracting actuation by said retractor carriage, dogging means movable to a first position for dogging said bolt and to a second position to clear the path of said bolt, and a cam slope on said 4dogging means and cooperating with a part of said sleeve for urging said clogging means toward said second position upon a retracting displacement of said sleeve, said bolt tail and said sleeve being positioned for independent coupling to the retractor CaIIllge.

2. In a latch device of the character indicated, a main bolt and an auxiliary bolt longitudinally slidable relatively to each other, latch-tail means for said main bolt including lug means rigidly carried by said main bolt for retracting actuation by a retractor carriage, interfering means movable into and out of a position to interfere with a retracting displacement of said main bolt, resilient means normally urging both said bolts into an outwardly extended position and also normally urging said interfering means in the direction of said interfering position, a cam on said interfering means, first cam-actuating means including lug means rigidly carried thereby and independent of said mst-mentioned iug means for retracting actuation by the retraotoi carriage. said rst cam-actuating means and said main bolt being relatively movable longitudinally, said cam and said iiist cam-actuating means cooperating to move said interfering means away from said interfering position upon a retracting actuation of the retractor carriage, and second camactuating means carried rigidly by said auxiliary bolt and cooperating with said cam to move said interfering means away from said interfering 10 Number 'position when said auxiliary beit; approaches a forwardly projected position.

NICHOLAS A. WELCH.

Name Date 1,876,081 Shg'e ..-nana- Sept. 6, 1932 

